The link between behaviour, calmness and feed

By Clare MacLeod

Normal equine behaviour
Given free choice, horses will spend a minimum of 50%, and up to 75% of their time grazing and browsing (Hothersall & Nicol, 2013). They choose to live in herds and, if given enough space, will cover many kilometres daily, depending on where their water source is.

Given the choice, horses will eat a variety of material including twigs, bark, leaves, soil and humus, as well as grass and other plant herbage. Grass tends to make up most of the preferred feed intake, however. Horses learn as foals to avoid poisonous plants. They appear to learn about food selection from each other, and normal ingestive behaviour develops in horses kept in groups (McGreevy, 2004). Horses can adapt to low energy diets or very short pasture grass by eating for longer, and may graze for 19 hours (79% of their time) if forage is in short supply (McGreevy, 2004).

Given choice, horses live in groups and spend up to three quarters of their time grazing and browsing.
Given choice, horses live in groups and spend up to three quarters of their time grazing and browsing.

The horse’s natural diet involves a large amount of chewing, and a horse foraging on high fibre material may chew up to 57 000 times per day. Horses produce saliva only when chewing, which moistens food balls for swallowing, and helps buffer stomach acid (due to its alkaline nature) (McGreevy, 2004).

Movement is a big part of a horse’s ingestive behaviour, because they tend to move over a large area whilst grazing and browsing, moving on after a couple of mouthfuls in a single area (McGreevy, 2004).

Effects of domestication
Our domestic horses’ motivations for behaviour have changed very little from their wild ancestors. Domestic horses in confined spaces will use their paddocks in a similar way to feral horses in terms of where they eat, where they defaecate and where they roll (Waran, 1997). Stabled horses fed ad lib forage will eat for around 60% of their time (Houpt, 2005). Once stabled, however, the horse’s choices are limited, primarily in movement, ingestion and social contact.

Despite being highly adaptable, a fact that has led to their domestication, horses have a limit to how well they can adapt to some of the environments and situations they are put in within domestication (Waran, 1997). Waran (1997) clearly states that welfare could be improved by ‘meeting the horse’s need to perform certain behaviours and behavioural patterns which can be identified from studies of feral populations’. Where choice of behaviour is limited or not possible, welfare is negatively affected (McGreevy, 2004), and restricting behaviour needs by not feeding an appropriate diet (e.g. by limiting forage intake) may induce a chronic stress response which will inhibit optimal performance in competition (McBride & Mills, 2012).

In addition, confinement in a stable or stall will cause a rebound increase in locomotion (McGreevy, 2004) –unsurprisingly – so owners can sometimes blame feed or forage for their horses being livelier when it could be the locomotion restriction caused by stabling, and not the feed or forage at all.

Confinement increases a horse’s motivation to move, so plenty of turnout can help a horse stay calmer when ridden.
Confinement increases a horse’s motivation to move, so plenty of turnout can help a horse stay calmer when ridden.

Stabled horses fed a restricted hay and starchy concentrate diet may chew half as many times as those fed ad lib hay, which has large consequences for stomach health, due to the dramatically reduced amount of saliva swallowed, as well as the effect of starch on the stomach environment.

Horses that do not behave as their owners want used to be classed as having ‘vices’ but now we know that ‘shortfalls in management’ cause much unwanted behaviours rather than the horse having a problem or malicious intent (McGreevy, 2004). Stereotypic behaviour – repetitive, seemingly pointless behaviours that are not seen in free-living feral horses – are usually a consequence of a barren environment and poor feeding practices, where the horse has been ‘pushed beyond its limits of adaptation’ (McGreevy, 2004). Oral stereotypies include crib-biting and wind-sucking. Sadly these behaviours persist even after good management and feeding practices are implemented.

Crib-biting can be a consequence of poor feeding practices.
Crib-biting can be a consequence of poor feeding practices.

It is clear that if we can manage our domestic horses keeping their normal behaviour in mind, we are likely to have a healthier, happier horse.

How horses learn – changing and shaping their behaviour
Horses have a remarkable ability to learn, which means they can learn things we don’t want them to as quickly as they can learn desired behaviour. Training involves subduing natural but unwanted behaviour, encouraging desirable natural behaviour and teaching the horse new behaviour (Nicol, 2005).

Associative learning occurs when horses make links between cues and outcomes, and rewarding behaviour you want means that that behaviour will be more likely to be repeated (McGreevy, 2004). Be careful what you reward – for example if your horse acts aggressively towards you every time before you feed him concentrate in a bucket, you are rewarding that aggression. Your horse is rewarded by comfort (for example returning to his herd) including removal of pressure (for example the use of your leg to cause the horse to move forwards) and by feed or treats. Motivation is important to training (McBride & Mills, 2012), and considering ‘what is in it for your horse’ may well help encourage desirable behaviour.

If you feed your horse after he has laid his ears back at you, you will encourage that behaviour to occur more often.
If you feed your horse after he has laid his ears back at you, you will encourage that behaviour to occur more often.

Horses can get used to something aversive to them by a process of habituation, which can help them cope with what they have to deal with in domestication, including what the rider asks of them. Understanding the natural fear response of the horse, a prey animal, will help their behaviour tremendously. Houpt (2006) states that ‘the motivation for most misbehaviour is fear’ with regards vets handling horses. If the owner helps habituate the horse to veterinary procedures, the horse will be less fearful and the situation will be safer and less stressful for everyone involved.

Physical causes of unwanted behaviour should always be eliminated before retraining is done (McGreevy, 2004), and then the horse should be treated as an individual and a long-term holistic view taken since quick fixes rarely give good results long-term, and strengthening the horse-human interactive bond both on the ground and under saddle gets the best results (McGreevy, 2004).

Physical causes of unwanted behaviour should always be eliminated first.
Physical causes of unwanted behaviour should always be eliminated first.

It is important to understand basic horse behaviour and learning processes if the horse’s behaviour is to be influenced, because this will make a much bigger difference than any changes in feed.

Effects of the diet on behaviour
We tend to consider our horse’s energy levels in their work to be the behaviour most linked to feed, but actually the development of abnormal behaviour due to inappropriate feeding (and management) is a more studied aspect of the link between diet and behaviour in horses

Stereotypic behaviour  may have a hereditary component, but generally its onset is linked to modern, intensive management practices (Harris, 2005). Exactly why horses start crib-biting or wind-sucking is not fully understood, but it may be a way of producing saliva to help neutralise stomach acid in horses who have been fasted for so long that their gastric acid build up causes discomfort (Hothersall & Nicol, 2013). Horses with stereotypies have a higher risk of colic, often struggle to maintain condition and have a lower market value (Hothersall & Nicol, 2013).

It is well known anecdotally that feeding starchy cereal-based concentrate feed can cause some horses to become more reactive and ‘fizzy’ (McGreevy, 2004) and one theory is that the behaviour is linked to a glycaemic effect. Feeding starch or sugar-rich meals will cause large fluctuations in blood glucose (sugar) and insulin, which in turn may cause the ‘fizzy’ or unwanted excitable and/or reactive behaviour (Hothersall & Nicol, 2013).

Feeding starchy cereal-based concentrate feed can cause some horses to become more reactive and ‘fizzy'.
Feeding starchy cereal-based concentrate feed can cause some horses to become more reactive and ‘fizzy’.

Replacing dietary starch and sugar with oil and highly digestible fibre can reduce reactivity, including spontaneous locomotion, to novel things (Kronfeld et al, 1999). Foals fed a fibre and oil based concentrate feed rather than a starch based one coped with weaning better (Kronfeld et al, 1999). It is clear that replacing starchy concentrate-based diets with highly digestible fibre and fat-supplemented diets can reduce unwanted effects of diet on behaviour, including the startle response, spooking, ability to concentrate and learn (Hothersall & Nicol, 2013).

Feed may also affect behaviour in another quite different way. Horses have a limited capacity for starch digestion in the foregut, and if this is overwhelmed, undigested starch will flow into the hindgut where it will be rapidly fermented, increasing acidity. This increased acidity can cause discomfort, is linked to abnormal behaviours such as crib-biting, and could cause increased anxiety and aggression. So it could be that visceral discomfort in the fore or hindgut may well be linked to the excitable, irritable or abnormal behaviour seen in horse fed high starch, low fibre diets. In addition, it has been proposed that hindgut acidosis may cause sub-clinical laminitis, which will cause pain or discomfort during riding (Hothersall & Nicol, 2013).

Starch-rich diets can cause gut disturbance and discomfort, which could in turn cause anxious or aggressive behaviour.
Starch-rich diets can cause gut disturbance and discomfort, which could in turn cause anxious or aggressive behaviour.

Exactly why reducing starch and replacing it with fibre and oil can help horse behaviour is still not well understood, but theories include alterations in blood glucose levels, gut disturbance, need to forage, and rate of energy supply.

Encouraging calm behaviour
Horses are prey animals who have strong fear and flight instincts (Harris, 2005). ‘Normal’ behaviour for horses could include spookiness, reactivity and sharp responses. Management, training and feeding practices can influence a horse’s behaviour, however.

Feeding practices that encourage calm behaviour
Certain feeding strategies that can in some cases help to reduce reactivity and help concentration and calmness are as follows:

  • Feed plenty of forage, aiming to fulfil as much of the horse’s dietary requirements as possible from fibrous forage (thus reducing reliance on concentrate feed)
  • Avoid fasting periods of over 4 hours to ensure digestive health and comfort
  • Do not overfeed dietary energy
  • Minimise dietary starch to a minimum for a reactive horse, and a maximum of 1 g per kilo bodyweight per meal for all horses, and restrict dietary sugar
  • Use the ‘safe’ energy from vegetable oil to help meet high energy requirements
  • Restrict lush grass intake and
  • Consider a supplement to support calmness
Feed plenty of forage, aiming to fulfil as much of the horse’s dietary requirements as possible from fibrous feeds.
Feed plenty of forage, aiming to fulfil as much of the horse’s dietary requirements as possible from fibrous feeds.

Management and training that encourages calm behaviour
Management and training are probably more important for calm behaviour than feeding. McBride and Mills (2012) state that: ‘Optimal environmental conditions, to maintain the horse at a high performance level, are those that facilitate the behavioural needs of the species, thus reducing the risk of a chronic stress situation’. This point will apply to all horses used for recreation, not just high performance horses. Inappropriate management that causes a chronic stress situation will not result in a calm, predictable horse.

Plenty of turnout, ideally in groups, helps to fulfil a horse’s behavioural needs, in turn helping to avoid a chronic stress situation.
Plenty of turnout, ideally in groups, helps to fulfil a horse’s behavioural needs, in turn helping to avoid a chronic stress situation.

A thorough understanding of how horses learn, of behaviour modification, and attentiveness to physical limitations and the presence of pain and/or discomfort will make a marked difference to a horse’s calmness and attentiveness under saddle and dramatically reduce or eliminate behavioural problems in the ridden horse (McGreevy and McLean, 2005). The emotional state of the rider also has an impact on the horse (McBride & Mills, 2012) so a calm rider will help to foster a calm horse. Exposing the horse in a gradual but consistent way to the riding (including competing) environment will help the horse to become less reactive (McBride & Mills, 2012).

Correct, consistent and empathetic training will foster a calm horse who is a pleasure to ride.
Correct, consistent and empathetic training will foster a calm horse who is a pleasure to ride.

Confinement in a stable or stall will cause a rebound increase in locomotion (McGreevy, 2004), which may include liveliness so an important factor in having a calm horse is to ensure as little confinement as possible.

Enriching the stable environment could help reduce a horse’s anxiety and help them to be more settled if they do have to be confined. The most important factor is to allow as much as possible, free choice of forage, to fulfil the horse’s requirement for ingestive behaviour including chewing. Doing so will reduce the effect of digestive discomfort adversely affecting the ridden horse. For good doers or others with low energy requirements, very low energy forage will need to be sourced.

Offer stabled horses plenty of forage to ensure healthy digestive function.
Offer stabled horses plenty of forage to ensure healthy digestive function.

Offering stabled horses a selection of different forages increases the time they spend in eating behaviour (Hothersall & Nicol, 2013),  which could also help them to be more settled and less likely to perform unwanted behaviours such as stereotypies and be more settled when ridden. Mirrors in stables can reduce weaving, probably by mimicking visual contact with a herd member (McAfee et al, 2002). Although putting mirrors in stables did not affect the time the horses spent ingesting, it is possible that they could affect a horse that was particularly affected by social isolation.

Conclusion
There is good evidence to show that modern feeding and management practices have an impact on horse behaviour, and that feeding and managing horses with their natural needs in mind is both beneficial to their health and welfare (Hothersall & Nicol, 2013) and may ameliorate some unwanted behaviour. An understanding of how horses learn and how to modify their behaviour with correct training will also help ensure a calm and attentive horse; probably more so than adjustments in the feeding regime.

References
Harris, P. (2005) Nutrition, behaviour and the role of supplements for calming horses: The veterinarian’s dilemma. The Veterinary Journal, 170; 10-11.

Hothersall, B. & Nicol, C. (2013) Effects of diet on behaviour – normal and abnormal. In Geor, R. J., Harris, P. A. & Coenen, M. (Eds) Equine Applied and Clinical Nutrition, Saunders Elsevier, Edinburgh.

Houpt, K. A. (2005) Maintenance behaviours. In ‘The Domestic Horse’, ed. D. Mills & S. McDonnell. Cambridge University Press, Cambridge.

Houpt, K. A. (2006) Why horse behaviour is important to the equine clinician. Equine Veterinary Journal, 38 (5); 386-387.

Kronfeld, D, Holland, J., Hoffman, R. & Harris, P. (1999) Dietary influences on behaviour and stress. The Role of the Horse in Europe. Equine Veterinary Journal Supplement, 28; 64.

McAfee, L. M., Mills, D. R. & Cooper, J. J. (2002) The use of mirrors for the control of stereotypic weaving behaviour in the stabled horse. Applied Animal Behaviour Science, 78 (2-4); 159-173.

McBride, S. & Mills, D. (2012) Psychological factors affecting equine performance. BMC Veterinary Research, 8:180 Accessed on 08.09.15 at www.biomedcentral.com/1746-6148/8/180

McGreevy, P. (2004) Equine Behaviour. A Guide for Veterinarians and Equine Scientists. Saunders, Edinburgh.

McGreevy, P. & McLean, A. (2005) Behavioural problems with the ridden horse. In ‘The Domestic Horse’, ed. D. Mills & S. McDonnell. Cambridge University Press, Cambridge.

Nicol, C. J. (2005) Learning abilities in the horse. In ‘The Domestic Horse’, ed. D. Mills & S. McDonnell. Cambridge University Press, Cambridge.

Waran, N. K. (1997) Can studies of feral horse behaviour be used for assessing domestic horse welfare? Equine Veterinary Journal, 29 (4); 249-251.

About Clare MacLeod

Clare MacLeod MSc RNutr is one of the UK’s few registered independent equine nutritionists who also has expertise in health and fitness. She advises private and commercial clients in all sectors of the horse world and is a hands-on horse owner herself. Clare is passionate about correct nutrition as a foundation for good health, without which peak fitness is not possible. She states “Good nutrition isn’t everything, but there’s nothing without it”.